The present invention relates to photomechanical imaging processes. More particularly, this invention relates to color imaging processes utilizing both a removable photostencil produced directly or indirectly on a support and a water-permeable, water-insoluble color medium.
The art describes photomechanical imaging processes utilizing photosensitive materials. For example, such materials can be used as photoresists in metal etching processes or color imaging processes such as that described in U.S. Pat. No. 3,258,337, wherein a transparent photoresist image is produced on a layer of ink on a support. The ink is redissolved and removed in those areas not protected by the transparent image, thus forming a colored ink image underlying a transparent resist image. Other processes add colorant to the photosensitive material, or in the case of the screen printing process, use a photosensitive material to produce a photostencil on a screen printing frame from which color images are produced.
The art, however, has sought a method for producing an original color copy, wherein the color copy also serves as a high quality color proof. Further, in the field of color reproduction, the cost of producing large sizes and limited quantities by a printing process, wherein images are produced by a transfer method from plate to stock, is often prohibitive. Thus a color image production process is desired for the direct formation of color images on a support by means of a mechanized, plateless system.
The art would also appreciate a process for producing multiple copies more economically than either an artist is able to do by hand or can be accomplished by a printing process.
The art has sought, moreover, photochemical imaging processes wherein the only solvents needed for developing and stripping steps are water or aqueous solutions.
Further, a method is desired in which multicolored images may be processed at one time with one exposure through a photomask on which the originals of these images are represented, providing none of the images are touching or overlapping. Such a method for handling multicolored designs would result in a reduction of processing time.
Additionally, a method is desired for producing one or more colored images on a colored background, in which the images are (1) in automatic register with the background image; and (2) produced using a single graphic object pattern or photomask with a single exposure and a single processing.
In photomechanical imaging processes, moreover, more accurate image resolution has been sought.
Further, the art has sought a method for producing by photomechanical means color proofs, including four-color process proofs, on a single support surface, with image resolution equaling that of fine printing.
The art has also sought an improved method for producing opaque images on such supports as transparent plastic films, aluminum foil and the like, for which the hiding power of opaque pigments such as titanium dioxide is required.
In accordance with the present invention, a method relating to photomechanical imaging processes has been discovered for producing an original color copy, wherein the color copy also serves as a high quality color proof. The present invention also provides for the direct formation of color images on a support by means of a mechanized, plateless system and thus reduces the cost of producing a large sized color image and limited quantities of color images.
Further, in certain embodiments of the present invention, only water or aqueous solvents are needed in the developing and stripping steps. The use of flammable organic solvents is thus avoided.
In the method of the present invention, moreover, multicolored images may be processed at one time with one exposure through a photomask on which the originals of these images are represented, providing none of the images are touching or overlapping.
The present invention also allows for producing one or more colored images on a colored background, wherein the images are in automatic register with the background image and are produced using a single photomask and a single exposure in a single processing.
Moreover, the present invention achieves more accurate image resolution and provides for producing color proofs, including four-colored process proofs on a single support surface, with image resolution equaling that of fine printing.
The present invention also provides a method for producing opaque images on such supports as transparent plastic films, aluminum foil and the like, for which the hiding power of opaque pigments such as titanium dioxide is required.
The present invention further provides for the multicolored reproduction of one or more graphic object patterns on a support medium.